Solid-state imaging device, manufacturing method thereof, and electronic apparatus

ABSTRACT

Disclosed herein is a solid-state imaging device including: a laminated semiconductor chip configured to be obtained by bonding two or more semiconductor chip sections to each other and be obtained by bonding at least a first semiconductor chip section in which a pixel array and a multilayer wiring layer are formed and a second semiconductor chip section in which a logic circuit and a multilayer wiring layer are formed to each other in such a manner that the multilayer wiring layers are opposed to each other and are electrically connected to each other; and a light blocking layer configured to be formed by an electrically-conductive film of the same layer as a layer of a connected interconnect of one or both of the first and second semiconductor chip sections near bonding between the first and second semiconductor chip sections. The solid-state imaging device is a back-illuminated solid-state imaging device.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of application Ser. No.14/867,476 filed Sep. 28, 2015, now U.S. Pat. No. 9,496,307, issued onNov. 15, 2016, which is a Continuation of application Ser. No.14/168,524, filed Jan. 30, 2014, now U.S. Pat. No. 9,171,875, issuedOct. 27, 2015, which is a Divisional of application Ser. No. 13/362,758,filed Jan. 31, 2012, now U.S. Pat. No. 8,669,602, issued Mar. 11, 2014,and claims priority to Japanese Patent Application JP 2011-024954 filedin the Japanese Patent Office on Feb. 8, 2011, the entire contents ofwhich is hereby incorporated by reference.

BACKGROUND

The present disclosure relates to a solid-state imaging device, amanufacturing method thereof, and an electronic apparatus including asolid-state imaging device, such as a camera.

The CMOS (Complementary Metal Oxide Semiconductor) solid-state imagingdevice is known as a solid-state imaging device and this CMOSsolid-state imaging device is widely used in digital still cameras,digital video camcorders, etc. In recent years, as the solid-stateimaging device mounted in a mobile apparatus such as a cellular phoneequipped with a camera and a personal digital assistant (PDA), the CMOSsolid-state imaging device, whose supply voltage is low, is frequentlyused in view of the power consumption and so forth.

In the CMOS solid-state imaging device, the unit pixel is formed with aphotodiode serving as a photoelectric converter and plural pixeltransistors. The CMOS solid-state imaging device has a pixel array(pixel area) in which the plural unit pixels are arranged in atwo-dimensional array manner and a peripheral circuit area. The pluralpixel transistors are formed of MOS transistors and are composed ofthree transistors, i.e. a transfer transistor, a reset transistor, andan amplification transistor, or four transistors further including aselection transistor in addition to these three transistors.

As such a CMOS solid-state imaging device, there have been proposedvarious related-art solid-state imaging devices configured as one deviceby electrically connecting a semiconductor chip in which the pixel arrayobtained by arranging plural pixels is formed to a semiconductor chip inwhich a logic circuit to execute signal processing is formed. Forexample, Japanese Patent Laid-open No. 2006-49361 discloses asemiconductor module obtained by connecting a back-illuminated imagesensor chip having a micro-pad for each pixel cell to a signalprocessing chip having a signal processing circuit and a micro-pad by amicro-bump.

WO2006/129762 discloses a semiconductor image sensor module obtained bystacking a first semiconductor chip including an image sensor, a secondsemiconductor chip including an analog/digital converter array, and athird semiconductor chip including a memory element array. The firstsemiconductor chip is connected to the second semiconductor chip via abump as an electrically-conductive connecting conductor. The secondsemiconductor chip is connected to the third semiconductor chip by apenetrating contact that penetrates the second semiconductor chip.

SUMMARY

The present applicant has proposed the following solid-state imagingdevice. Specifically, the solid-state imaging device is obtained bybonding a semiconductor chip section including a pixel array and asemiconductor chip section including a logic circuit to each other. Thesolid-state imaging device is allowed to achieve higher performance sothat the respective semiconductor chip sections can sufficiently exerttheir performance, and is allowed to achieve higher mass-productivityand cost reduction. For manufacturing of this solid-state imagingdevice, the first semiconductor chip section including the pixel arrayand the second semiconductor chip section including the logic circuit,both of which are in a semi-product state, are bonded to each other.Then, the first semiconductor chip section is processed into a thin filmform and thereafter the pixel array is connected to the logic circuit.The connection is established by forming a connecting interconnectcomposed of: a connecting conductor connected to the requisiteinterconnect of the first semiconductor chip section; a penetratingconnecting conductor that penetrates the first semiconductor chipsection and is connected to the requisite interconnect of the secondsemiconductor chip section; and a coupling conductor that links bothconnecting conductors. Thereafter, this component obtained by thebonding is processed into a finished-product state and turned to a chipso as to be configured as a back-illuminated solid-state imaging device.

Meanwhile, as a new technique for the above-described solid-stateimaging device obtained by bonding the first semiconductor chip sectionand the second semiconductor chip section, there has been devised amethod in which the connection is established not by the electricalconnecting method using the penetrating connecting conductor but byguiding copper (Cu) electrodes to the surfaces of both semiconductorchip sections.

FIG. 22 shows a solid-state imaging device as one example of thistechnique. A back-illuminated CMOS solid-state imaging device 121 of thepresent example is configured as one device by bonding a firstsemiconductor chip section 122 and a second semiconductor chip section123. In the first semiconductor chip section 122, a pixel array 124composed of an effective pixel area 125 and an optical black area 126that outputs an optical reference black level is formed. In the secondsemiconductor chip section 123, a logic circuit 127 serving as theperipheral circuit is formed.

In the first semiconductor chip section 122, the pixel array 124 inwhich plural pixels each including a photodiode PD serving as aphotoelectric converter and plural pixel transistors Tr1 and Tr2 aretwo-dimensionally arranged in a matrix is formed in a firstsemiconductor substrate 131 formed of silicon processed into a thin filmform. On the side of a front surface 131 a of the semiconductorsubstrate 131, a multilayer wiring layer 134 is formed in whichinterconnects 133 [133 a to 133 d] and 142 formed of metals M1 to M5 ofplural layers, e.g. five layers in this example, are disposed by theintermediary of an interlayer insulating film 112. Copper (Cu)interconnects are used as the interconnects 133 and 142. On the backsurface side of the semiconductor substrate 131, a light blocking film136 covering the area over the optical black area 126 is formed by theintermediary of an insulating film 135. Furthermore, a color filter 138and an on-chip lens 139 are formed by the intermediary of a planarizingfilm 130.

In FIG. 22, the pixel transistors Tr1 and Tr2 are shown asrepresentatives of the plural pixel transistors. Although FIG. 22schematically shows the pixels of the pixel array 124, the details ofone pixel are shown in FIG. 23. In the first semiconductor chip 122, thephotodiode PD is formed in the semiconductor substrate 131 processedinto a thin film form. The photodiode PD has e.g. an n-typesemiconductor region 135 and a p-type semiconductor region 136 on thesubstrate surface side. Over the substrate surface to configure thepixels, gate electrodes 137 are formed by the intermediary of gateinsulating films and the pixel transistors Tr1 and Tr2 are each formedby the gate electrode 137 and a pair of source and drain regions 138.The pixel transistor Tr1 adjacent to the photodiode PD is equivalent toa floating diffusion FD. Each unit pixel is isolated by an elementisolation region 139.

In the multilayer wiring layer 134 of the first semiconductor chipsection 122, connection is established via electrically-conductive vias141 between the corresponding pixel transistor and the interconnect 133and between the interconnects 133 of upper and lower layers adjacent toeach other. Furthermore, the connecting interconnect 142 formed of thefifth-layer metal M5 is so formed as to face the bonding surface to thesecond semiconductor chip section 123. The connecting interconnect 142is connected to the requisite interconnect 133 d formed of thefourth-layer metal M4 via the electrically-conductive vias 141.

In the second semiconductor chip section 123, the logic circuit 127serving as the peripheral circuit is formed in the area serving as eachchip section in a second semiconductor substrate 143 formed of silicon.The logic circuit 127 is formed by plural MOS transistors Tr11 to Tr14including a CMOS transistor. Over the front surface side of thesemiconductor substrate 143, a multilayer wiring layer 147 is formed inwhich interconnects 145 [145 a to 145 c] and a connecting interconnect146 formed of metals M11 to M14 of plural layers, e.g. four layers inthis example, are disposed by the intermediary of an interlayerinsulating film 144. Copper (Cu) interconnects are used as theinterconnects 145.

In FIG. 22, the MOS transistors Tr11 to Tr14 are shown asrepresentatives of the plural MOS transistors of the logic circuit 127.Although FIG. 22 schematically shows the MOS transistors Tr11 to Tr14,the details of e.g. the MOS transistors Tr11 and Tr12 are shown in FIG.24. In the second semiconductor chip section 123, each of the MOStransistors Tr11 and Tr12 is so formed as to have a pair of source anddrain regions 149 and a gate electrode 151 formed by the intermediary ofa gate insulating film in a semiconductor well region on the frontsurface side of the semiconductor substrate 143. Each of the MOStransistors Tr11 and Tr12 is isolated by an element isolation region152.

In the multilayer wiring layer 147 of the second semiconductor chipsection 123, connection is established via electrically-conductive vias153 between the MOS transistors Tr11 to Tr14 and the interconnect 145and between the interconnects 145 of upper and lower layers adjacent toeach other. Furthermore, the connecting interconnect 146 formed of thefourth-layer metal M14 is so formed as to face the bonding surface tothe first semiconductor chip section 122. The connecting interconnect146 is connected to the requisite interconnect 145 c formed of thethird-layer metal M13 via the electrically-conductive via 153.

The first semiconductor chip section 122 and the second semiconductorchip section 123 are electrically connected to each other in such amanner that their respective multilayer wiring layers 134 and 147 areopposed to each other and the connecting interconnects 142 and 146facing the bonding surface are bonded directly to each other. Aninsulating film 154 near the bonding is formed of a Cu diffusion barrierinsulating film for preventing Cu diffusion of the Cu interconnect.

By the way, it has turned out that, in the above-described solid-stateimaging device 121, light emission due to hot carriers from the MOStransistor in the logic circuit 127 is incident on the pixel array sideand this light incidence causes dark current and random noise.Therefore, a light blocking layer needs to be provided between the firstsemiconductor chip section 122, in which the pixel array is formed, andthe second semiconductor chip section 123, in which the logic circuit isformed. In FIG. 22, in the multilayer wiring layer 134 of the firstsemiconductor chip section 122, a light blocking layer 155 is formedseparately from the interconnects 133.

To form the light blocking layer 155 between the first and secondsemiconductor chip sections 122 and 123, it is necessary to form thelight blocking layer 155, and to carry out electrical isolation andinterconnect forming for wiring between the first and secondsemiconductor chip sections, so that the number of steps becomes large.Furthermore, the light blocking layer 155 needs to have asufficiently-large film thickness to attenuate light. The existence ofthis light blocking layer 155 increases the thickness of the wholesemiconductor chip obtained by bonding the first and secondsemiconductor chip sections 122 and 123 and extends the distance of theelectrical interconnect forming. This increases the technical difficultyin the interconnect forming and causes problems such as lowering of themanufacturing yield of the solid-state imaging device.

The present disclosure has been made in view of the above circumstancesand provides a solid-state imaging device and a manufacturing methodthereof that suppress the thickness of the whole semiconductor chip,suppress the adverse effects of light emission due to hot carriers froma transistor, and allow reduction in the number of steps.

The present disclosure also provides an electronic apparatus that can beapplied to e.g. a camera including such a solid-state imaging device.

According to one embodiment of the present disclosure, there is provideda solid-state imaging device including: a laminated semiconductor chipconfigured to be obtained by bonding two or more semiconductor chipsections to each other and be obtained by bonding at least a firstsemiconductor chip section in which a pixel array and a multilayerwiring layer are formed and a second semiconductor chip section in whicha logic circuit and a multilayer wiring layer are formed to each otherin such a manner that the multilayer wiring layers are opposed to eachother and are electrically connected to each other; and a light blockinglayer configured to be formed by an electrically-conductive film of thesame layer as a layer of a connected interconnect of one or both of thefirst and second semiconductor chip sections near bonding between thefirst and second semiconductor chip sections. The solid-state imagingdevice is configured as a back-illuminated solid-state imaging device.

In the solid-state imaging device according to the embodiment of thepresent disclosure, the light blocking layer is formed by theelectrically-conductive film of the same layer as that of the connectedinterconnect of one or both of the first and second semiconductor chipsections near the bonding between the first and second semiconductorchip sections. Thus, emitted light due to hot carriers from a transistorof the logic circuit is prevented by the light blocking layer and theincidence thereof on the pixel array side is suppressed. Furthermore,the thickness of the whole semiconductor chip after the bonding is alsosuppressed.

According to another embodiment of the present disclosure, there isprovided a manufacturing method of a solid-state imaging device. Themethod includes: forming at least a pixel array and a multilayer wiringlayer in an area to serve as a first semiconductor chip section in afirst semiconductor wafer; forming at least a logic circuit and amultilayer wiring layer in an area to serve as a second semiconductorchip section in a second semiconductor wafer. The method also includesforming a light blocking layer by an electrically-conductive film of thesame layer as a layer of a connected interconnect in the multilayerwiring layer of one or both of the first semiconductor wafer and thesecond semiconductor wafer. The method further includes: bonding two ormore semiconductor wafers including at least the first and secondsemiconductor wafers in such a manner that the multilayer wiring layersof the first semiconductor wafer and the second semiconductor wafer areopposed to each other and interconnects of both wafers are electricallyconnected to each other; processing the first semiconductor wafer into athin film form; and processing the bonded semiconductor wafers into achip.

In the manufacturing method of a solid-state imaging device according tothe embodiment of the present disclosure, the light blocking layerformed by the electrically-conductive film of the same layer as that ofthe connected interconnect is formed in the multilayer wiring layer ofone or both of the first semiconductor wafer and the secondsemiconductor wafer. Furthermore, the first and second semiconductorwafers are so bonded to each other that their respective multilayerwiring layers are opposed to each other and the interconnects of bothwafers are electrically connected to each other. This enablesmanufacturing a solid-state imaging device having the followingfeatures. Specifically, the thickness of the whole semiconductor chipafter the bonding is suppressed. In addition, emitted light due to hotcarriers from a transistor of the logic circuit is blocked by the lightblocking layer and the incidence thereof on the pixel array side issuppressed.

According to further embodiment of the present disclosure, there isprovided an electronic apparatus including a solid-state imaging device,an optical system that guides incident light to a photoelectricconverter of the solid-state imaging device, and a signal processingcircuit that processes an output signal of the solid-state imagingdevice. The solid-state imaging device is configured by the solid-stateimaging device according to the above-described embodiment of thepresent disclosure.

The electronic apparatus according to the embodiment of the presentdisclosure includes the solid-state imaging device having theabove-described configuration as its solid-state imaging device.Therefore, in the solid-state imaging device, the thickness of the wholesemiconductor chip after the bonding is suppressed. In addition, emittedlight due to hot carriers from a transistor of the logic circuit isblocked by the light blocking layer and the incidence thereof on thepixel array side is suppressed.

The solid-state imaging device and the manufacturing method thereofaccording to the embodiments of the present disclosure can suppress thethickness of the whole semiconductor chip and suppress the adverseeffects of light emission due to hot carriers from a transistor.Furthermore, they enable reduction in the number of manufacturing steps.

The electronic apparatus according to the embodiment of the presentdisclosure includes a solid-state imaging device based on bonded chipsin which the adverse effects of light emission due to hot carriers froma transistor are suppressed. This can provide an electronic apparatussuch as a high-quality camera.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram showing one example of aCMOS solid-state imaging device applied to an embodiment of the presentdisclosure;

FIGS. 2A to 2C are schematic diagrams of solid-state imaging devicesaccording to embodiments of the present disclosure and a solid-stateimaging device according to a related-art example;

FIG. 3 is a schematic configuration diagram of a major part, showing asolid-state imaging device according to a first embodiment of thepresent disclosure;

FIG. 4 is an enlarged configuration diagram showing a major part of afirst semiconductor chip section in FIG. 3;

FIG. 5 is an enlarged configuration diagram showing a major part of asecond semiconductor chip section in FIG. 3;

FIG. 6 is an enlarged configuration diagram showing a major part of abonding part in FIG. 3;

FIGS. 7A to 7C are configuration diagrams showing a light blocking layerin the first embodiment;

FIG. 8 is a manufacturing process diagram (first diagram) showing amanufacturing method example of the solid-state imaging device accordingto the first embodiment;

FIG. 9 is a manufacturing process diagram (second diagram) showing themanufacturing method example of the solid-state imaging device accordingto the first embodiment;

FIG. 10 is a manufacturing process diagram (third diagram) showing themanufacturing method example of the solid-state imaging device accordingto the first embodiment;

FIG. 11 is a manufacturing process diagram (fourth diagram) showing themanufacturing method example of the solid-state imaging device accordingto the first embodiment;

FIG. 12 is a manufacturing process diagram (fifth diagram) showing themanufacturing method example of the solid-state imaging device accordingto the first embodiment;

FIG. 13 is a manufacturing process diagram (sixth diagram) showing themanufacturing method example of the solid-state imaging device accordingto the first embodiment;

FIG. 14 is a manufacturing process diagram (seventh diagram) showing themanufacturing method example of the solid-state imaging device accordingto the first embodiment;

FIG. 15 is a manufacturing process diagram (eighth diagram) showing themanufacturing method example of the solid-state imaging device accordingto the first embodiment;

FIG. 16 is a manufacturing process diagram (ninth diagram) showing themanufacturing method example of the solid-state imaging device accordingto the first embodiment;

FIG. 17 is a graph that is used for explaining an embodiment of thepresent disclosure and shows the dependence of the light transmittanceon the wavelength regarding a specific film thickness;

FIG. 18 is a graph that is used for explaining an embodiment of thepresent disclosure and shows the dependence of the light transmittanceon the film thickness of a metal film regarding a specific wavelength;

FIGS. 19A to 19C are configuration diagrams showing a modificationexample of the light blocking layer according to the embodiment;

FIG. 20 is a schematic configuration diagram of a major part, showing asolid-state imaging device according to a second embodiment of thepresent disclosure;

FIG. 21 is a schematic configuration diagram of an electronic apparatusaccording to a third embodiment of the present disclosure;

FIG. 22 is a schematic configuration diagram of a major part of asolid-state imaging device according to a related-art example;

FIG. 23 is an enlarged configuration diagram showing a major part of afirst semiconductor chip section in FIG. 22; and

FIG. 24 is an enlarged configuration diagram showing a major part of asecond semiconductor chip section in FIG. 22.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Modes for carrying out the technique of the present disclosure(hereinafter, referred to as the embodiments) will be described below.The order of the description is as follows.

1. Schematic Configuration Example of CMOS Solid-state Imaging Device

2. First Embodiment (configuration example of solid-state imaging deviceand manufacturing method example thereof)

3. Second Embodiment (configuration example of solid-state imagingdevice and manufacturing method example thereof)

4. Third Embodiment (configuration example of electronic apparatus)

1. Schematic Configuration Example of CMOS Solid-State Imaging Device

FIG. 1 shows the schematic configuration of a CMOS solid-state imagingdevice applied to a semiconductor device of one embodiment of thepresent disclosure. This CMOS solid-state imaging device is applied tosolid-state imaging devices of the respective embodiments. As shown inFIG. 1, a solid-state imaging device 1 of the present example has apixel array (so-called pixel area) 3 in which plural pixels 2 eachincluding a photoelectric converter are regularly arranged in atwo-dimensional array manner and a peripheral circuit section over asemiconductor substrate 11, e.g. a silicon substrate. The pixel 2 hase.g. a photodiode serving as the photoelectric converter and pluralpixel transistors (so-called MOS (Metal-Oxide Semiconductor)transistor). The plural pixel transistors can be configured by e.g.three transistors, i.e. a transfer transistor, a reset transistor, andan amplification transistor. Alternatively, it is also possible to add aselection transistor to configure the pixel transistors by fourtransistors. The equivalent circuit of the unit pixel is similar to anormal circuit and therefore detailed description thereof is omitted.The pixel 2 can be configured as one unit pixel. It is also possible forthe pixel 2 to have a sharing pixel structure. This pixel sharingstructure is composed of plural photodiodes, plural transfertransistors, shared one floating diffusion, and a shared respective oneof the other pixel transistors. That is, in the sharing pixel, thephotodiodes and the transfer transistors of plural unit pixels share arespective one of the other pixel transistors.

The peripheral circuit section has a vertical drive circuit 4, columnsignal processing circuits 5, a horizontal drive circuit 6, an outputcircuit 7, a control circuit 8, and so forth.

The control circuit 8 receives an input clock and data to order theoperation mode and so forth, and outputs data of internal information ofthe solid-state imaging device and so forth. Specifically, the controlcircuit 8 generates a clock signal and a control signal serving as thebasis of the operation of the vertical drive circuit 4, the columnsignal processing circuits 5, the horizontal drive circuit 6, and soforth based on a vertical synchronizing signal, a horizontalsynchronizing signal, and a master clock. The control circuit 8 inputsthese signals to the vertical drive circuit 4, the column signalprocessing circuits 5, the horizontal drive circuit 6, and so forth.

The vertical drive circuit 4 is configured with e.g. a shift register.The vertical drive circuit 4 selects a pixel drive interconnect andsupplies a pulse for driving the pixel to the selected pixel driveinterconnect to drive the pixels on a row-by-row basis. Specifically,the vertical drive circuit 4 performs selective scanning of therespective pixels 2 of the pixel array 3 on a row-by-row basissequentially in the vertical direction and supplies a pixel signal basedon a signal charge generated depending on the amount of received lightin e.g. the photodiode serving as the photoelectric converter of each ofthe pixel 2 to the column signal processing circuits 5 via verticalsignal lines 9.

The column signal processing circuits 5 are disposed for each column ofthe pixels 2 for example and execute signal processing such as noiseremoval for signals output from the pixels 2 on one row on each pixelcolumn basis. Specifically, the column signal processing circuits 5execute signal processing such as CDS (Correlated Double Sampling) forremoving fixed pattern noise specific to the pixel 2, signalamplification, and AD (Analog-to-Digital) conversion. At the outputstage of the column signal processing circuits 5, a horizontal selectionswitch (not shown) is so provided as to be connected to a horizontalsignal line 10.

The horizontal drive circuit 6 is configured with e.g. a shift register.The horizontal drive circuit 6 sequentially outputs a horizontalscanning pulse to thereby select each of the column signal processingcircuits 5 in turn and make the pixel signal be output from each of thecolumn signal processing circuits 5 to the horizontal signal line 10.

The output circuit 7 executes signal processing for the signalsequentially supplied from each of the column signal processing circuits5 via the horizontal signal line 10 and outputs the resulting signal.For example, the output circuit 7 performs only buffering in some cases,and executes black level adjustment, column variation correction,various kinds of digital signal processing, etc. in other cases.Input/output terminals 12 exchange signals with the external.

FIGS. 2A to 2C show the basic schematic configurations of a related-artCMOS solid-state imaging device and CMOS solid-state imaging devicesaccording to embodiments of the present disclosure. As shown in FIG. 2A,a related-art CMOS solid-state imaging device 161 is configured bymounting a pixel array 163, a control circuit 164, and a logic circuit165 for signal processing in one semiconductor chip 162. Normally animage sensor 166 is configured by the pixel array 163 and the controlcircuit 164. In contrast, as shown in FIG. 2B, in a CMOS solid-stateimaging device 20 according to one embodiment of the present disclosure,a pixel array 23 and a control circuit 24 are mounted in a firstsemiconductor chip section 22 and a logic circuit 25 including a signalprocessing circuit for signal processing is mounted in a secondsemiconductor chip section 26. The first and second semiconductor chipsections 22 and 26 are electrically connected to each other to configurethe CMOS solid-state imaging device 20 as one semiconductor chip. Asshown in FIG. 2C, in a CMOS solid-state imaging device 21 according toanother embodiment of the present disclosure, the pixel array 23 ismounted in the first semiconductor chip section 22 and the controlcircuit 24 and the logic circuit 25 including the signal processingcircuit are mounted in the second semiconductor chip section 26. Thefirst and second semiconductor chip sections 22 and 26 are electricallyconnected to each other to configure the CMOS solid-state imaging device21 as one semiconductor chip.

It is also possible to configure a CMOS solid-state imaging device bybonding three or more semiconductor chip sections to each otherdepending on the configuration of the CMOS solid-state imaging device,although not shown in the diagram. For example, it is also possible toconfigure a CMOS solid-state imaging device made as one chip by adding asemiconductor chip section including a memory element array, asemiconductor chip section including another circuit element, and soforth besides the above-described first and second semiconductor chipsections and bonding three or more semiconductor chip sections to eachother.

2. First Embodiment Configuration Example of Solid-State Imaging Device

FIG. 3 shows a solid-state imaging device according to one embodiment ofthe present disclosure, specifically a back-illuminated CMOS solid-stateimaging device according to a first embodiment of the presentdisclosure. A solid-state imaging device 31 according to the firstembodiment has a laminated semiconductor chip 32 obtained by bonding thefirst semiconductor chip section 22 in which the pixel array 23 and thecontrol circuit 24 are formed and the second semiconductor chip section26 in which the logic circuit 25 is formed, similar to those shown inFIG. 2B. The first semiconductor chip section 22 is bonded to the secondsemiconductor chip section 26 in such a manner that their respectivemultilayer wiring layers to be described later are opposed to each otherand that connecting interconnects are bonded directly to each other.

In the first semiconductor chip section 22, a pixel array 160 in whichplural pixels each including a photodiode PD serving as thephotoelectric converter and plural pixel transistors Tr1 and Tr2 aretwo-dimensionally arranged in a matrix is formed in a firstsemiconductor substrate 33 formed of silicon processed into a thin filmform. Furthermore, plural MOS transistors configuring the controlcircuit 24 are formed on the semiconductor substrate 33 although notshown in the diagram. On the side of a front surface 33 a of thesemiconductor substrate 33, a multilayer wiring layer 37 is formed inwhich interconnects 35 [35 a to 35 d] and 36 formed of metals M1 to M5of plural layers, e.g. five layers in this example, are disposed by theintermediary of an interlayer insulating film 34. Copper (Cu)interconnects formed by a dual damascene method are used as theinterconnects 35 and 36. On the back surface side of the semiconductorsubstrate 33, a light blocking film 39 covering the area over an opticalblack area 41 is formed by the intermediary of an insulating film 38.Furthermore, a color filter 44 and an on-chip lens 45 are formed over aneffective pixel area 42 by the intermediary of a planarizing film 43. Itis also possible to form the on-chip lens 45 also over the optical blackarea 41.

In FIG. 3, the pixel transistors Tr1 and Tr2 are shown asrepresentatives of the plural pixel transistors. Although FIG. 3schematically shows the pixels of the pixel array 160, the details ofone pixel are shown in FIG. 4. In the first semiconductor chip 22, thephotodiode PD is formed in the semiconductor substrate 33 processed intoa thin film form. The photodiode PD has e.g. an n-type semiconductorregion 46 and a p-type semiconductor region 47 on the substrate surfaceside. Over the substrate surface to configure the pixels, gateelectrodes 48 are formed each by the intermediary of a gate insulatingfilm and the pixel transistors Tr1 and Tr2 are each formed by the gateelectrode 48 and a pair of source and drain regions 49. The pixeltransistor Tr1 adjacent to the photodiode PD is equivalent to a floatingdiffusion FD. Each unit pixel is isolated by an element isolation region51. The element isolation region 51 is formed into a shallow trenchisolation (STI) structure obtained by burying an insulating film such asan SiO₂ film in trenches formed in the substrate for example.

In the multilayer wiring layer 37 of the first semiconductor chipsection 22, connection is established via electrically-conductive vias52 between the corresponding pixel transistor and the interconnect 35and between the interconnects 35 of upper and lower layers adjacent toeach other. Furthermore, the connecting interconnect 36 formed of thefifth-layer metal M5 is so formed as to face a bonding surface 40 to thesecond semiconductor chip section 26. The connecting interconnect 36 isconnected to the requisite interconnect 35 d formed of the fourth-layermetal M4 via the electrically-conductive vias 52.

In the second semiconductor chip section 26, a logic circuit 55 servingas the peripheral circuit is formed in the area serving as each chipsection in a second semiconductor substrate 54 formed of silicon. Thelogic circuit 55 is formed by plural MOS transistors Tr11 to Tr14including a CMOS transistor. Over the front surface side of thesemiconductor substrate 54, a multilayer wiring layer 59 is formed inwhich interconnects 57 [57 a to 57 c] and 58 formed of metals M11 to M14of plural layers, e.g. four layers in this example, are disposed by theintermediary of an interlayer insulating film 56. Copper (Cu)interconnects by the dual damascene method are used as the interconnects57 and 58.

In FIG. 3, the MOS transistors Tr11 to Tr14 are shown as representativesof the plural MOS transistors of the logic circuit 55. Although FIG. 3schematically shows the MOS transistors Tr11 to Tr14, the details ofe.g. the MOS transistors Tr11 and Tr12 are shown in FIG. 5. In thesecond semiconductor chip section 26, each of the MOS transistors Tr11and Tr12 is so formed as to have a pair of source and drain regions 61and a gate electrode 62 formed by the intermediary of a gate insulatingfilm in a semiconductor well region on the front surface side of thesemiconductor substrate 54. Each of the MOS transistors Tr11 and Tr12 isisolated by an element isolation region 63 having e.g. the STIstructure.

In the multilayer wiring layer 59 of the second semiconductor chipsection 26, connection is established via electrically-conductive vias64 between the MOS transistors Tr11 to Tr14 and the interconnect 57 andbetween the interconnects 57 of upper and lower layers adjacent to eachother. Furthermore, the connecting interconnect 58 formed of thefourth-layer metal M14 is so formed as to face the bonding surface 40 tothe first semiconductor chip section 22. The connecting interconnect 58is connected to the requisite interconnect 57 c formed of thethird-layer metal M13 via the electrically-conductive vias 64.

The first semiconductor chip section 22 and the second semiconductorchip section 26 are electrically connected to each other in such amanner that their respective multilayer wiring layers 37 and 59 areopposed to each other and the connecting interconnects 36 and 58 facingthe bonding surface 40 are bonded directly to each other. Interlayerinsulating films 66 near the bonding are formed of the combination of aCu diffusion barrier insulating film for preventing Cu diffusion of theCu interconnects and an insulating film that does not have the Cudiffusion barrier character as shown in a manufacturing method to bedescribed later. The direct bonding between the connecting interconnects36 and 58 formed of Cu interconnects is carried out by thermal diffusionbonding. The bonding between the insulating films 66 at the bondingsurfaces on which neither the connecting interconnect 36 nor 58 existsis carried out by plasma bonding or an adhesive.

In the present embodiment, particularly as shown in FIG. 3 and FIG. 6(enlarged diagram of the major part), a light blocking layer 68 formedof electrically-conductive films of the same layers as those of theconnecting interconnects is formed near the bonding between the firstand second semiconductor chip sections 22 and 26. The light blockinglayer 68 of the present embodiment is formed by a light blockingcomponent 71 formed of the metal M5 of the same layer as that of theconnecting interconnect 36 of the first semiconductor chip section 22and a light blocking component 72 formed of the metal M14 of the samelayer as that of the connecting interconnect 58 of the secondsemiconductor chip section 26. In this case, as shown in FIGS. 7A to 7C,either one of the light blocking components 71 or 72, i.e. the lightblocking component 71 in the present example, is formed into a shapehaving plural apertures 73 at predetermined pitches in the vertical andhorizontal directions in top view (see FIG. 7A). Furthermore, the otherlight blocking component 72 is formed into a shape of dots covering theapertures 73 of the light blocking component 71 in top view (see FIG.7B). The light blocking layer 68 is so configured that both lightblocking components 71 and 72 overlap with each other in such a state asto uniformly cover the surface in top view (see FIG. 7C).

The light blocking component 71 and the light blocking component 72covering the apertures 73 of the light blocking component 71 are soformed as to partially overlap with each other. When the connectinginterconnects 36 and 58 are bonded directly to each other, the lightblocking component 71 and the light blocking component 72 are bondeddirectly to each other at the simultaneously-overlapped part. Variousshapes are possible as the shape of the apertures 73 of the lightblocking component 71. In the diagram, each of the apertures 73 isformed into a rectangular shape. The light blocking component 72 in adot manner has a shape covering the apertures 73. In the diagram, eachdot of the light blocking component 72 is formed into a rectangularshape having an area somewhat larger than that of the corresponding oneof the apertures 73. It is preferable that a fixed potential, e.g. theground potential, be applied to the light blocking layer 68 so that thelight blocking layer 68 may be stable in terms of the potential.

Manufacturing Method Example of Solid-State Imaging Device

FIGS. 8 to 16 show a manufacturing method example of the solid-stateimaging device 31 according to the first embodiment. FIGS. 8 to 10 showsteps for the first semiconductor chip section having the pixel array.FIGS. 11 to 13 show steps for the second semiconductor chip sectionhaving the logic circuit. FIGS. 14 to 16 show steps of bonding and thesubsequent processing.

First, as shown in FIG. 8, a semiconductor well region 30 is formed inthe area to serve as each chip section in the first semiconductor wafer(hereinafter, referred to as the semiconductor substrate) 33 formed ofe.g. silicon, and the photodiodes PD serving as the photoelectricconverters of the respective pixels are formed in this semiconductorwell region 30. The element isolation region 51 (see FIG. 4) can beformed at first although not shown in the diagram. Each photodiode PD isso formed as to be extended in the depth direction of the semiconductorwell region 30. The photodiodes PD are formed in the effective pixelarea 42 and the optical black area 41, both of which configure the pixelarray 160.

Furthermore, plural pixel transistors configuring the respective pixelsare formed on the front surface side of the semiconductor well region30. The pixel transistors can be configured by e.g. a transfertransistor, a reset transistor, an amplification transistor, and aselection transistor. Here, the pixel transistors Tr1 and Tr2 are shownas representatives as described above. Each of the pixel transistors Tr1and Tr2 has the pair of source and drain regions and the gate electrodeformed by the intermediary of the gate insulating film although notshown in the diagram.

Over the front surface side of the semiconductor substrate 33, theinterconnects 35 [35 a, 35 b, 35 c and 35 d] formed of the metals M1 toM4 of plural layers, i.e. four layers in the present example, areformed, including the electrically-conductive vias 52, by theintermediary of the interlayer insulating film 34. The interconnects 35can be formed by a dual damascene method. Specifically, a connectinghole and an interconnect trench by a via-first process aresimultaneously formed in the interlayer insulating film 34, and a Cudiffusion barrier metal film for preventing Cu diffusion and a Cu seedfilm are formed. Thereafter, a Cu material layer is buried by a platingmethod. Examples of the Cu diffusion barrier metal film include Ta, TaN,Ti, TiN, W, WN, Ru, TiZrN films, and alloy films containing thesematerials. Subsequently, the excess Cu material layer is removed by achemical mechanical polishing (CMP) method, so that a Cu interconnectmonolithic with the planarized electrically-conductive via is formed.Thereafter, the Cu diffusion barrier insulating film is depositedalthough not shown in the diagram. As the Cu diffusion barrierinsulating film, e.g. an insulating film of SiN, SiC, SiCN, or SiON orbenzocyclobutene (BCB: adhesive) as a resin can be used. By repeatingthis step, the interconnects 35 a to 35 d formed of the metals M1 to M4of four layers are formed.

Next, as shown in FIG. 9, a first insulating film 76 that does not havethe Cu diffusion barrier character, a second insulating film 77 thatdoes not have the Cu diffusion barrier character, and a Cu diffusionbarrier insulating film 75 are sequentially formed. The first insulatingfilm 76 and the second insulating film 77 are formed of an SiO₂ film, anSiCOH film, etc. As the Cu diffusion barrier insulating film 75, e.g. aninsulating film of SiN, SiC, SiCN, or SiON or benzocyclobutene (BCB:adhesive) as a resin can be used as with the above description. The Cudiffusion barrier insulating film 75, the first insulating film 76, andthe second insulating film 77 are equivalent to the interlayerinsulating film 34. Subsequently, the outermost Cu diffusion barrierinsulating film 75, the second insulating film 77, and the firstinsulating film 76 are patterned to selectively open via holes 80 by avia-first process by using lithography and etching technique.Thereafter, the second insulating film 77 is patterned to selectivelyform apertures 78 and 79. That is, the films are so patterned as to havethe apertures 78 at the parts corresponding to the light blockingcomponent 71 (part except the apertures 73) that should be formed, theaperture 79 at the part corresponding to the connecting interconnect 36that should be formed, and the via holes 80.

Next, as shown in FIG. 10, the light blocking component 71 having theapertures 73, the electrically-conductive vias 52 connected to theinterconnect 35 d, and the connecting interconnect 36 are formed byburying a Cu material in the apertures 78 and 79 and the via holes 80 byuse of the dual damascene method as with the above description. Thelight blocking component 71 and the connecting interconnect 36 areformed by the fifth-layer metal M5. Thereby, the multilayer wiring layer37 is formed by the interconnects 35 a to 35 d, the connectinginterconnect 36, the light blocking component 71, which are formed ofthe metals M1 to M5, the interlayer insulating films 34, the Cudiffusion barrier insulating film 75, the first insulating film 76, andthe second insulating film 77. It is preferable that an interconnect 35d 1 formed of the fourth-layer metal M4 connected to the connectinginterconnect 36 be so formed as to be sufficiently extended to the sideof the light blocking component 71 and have such an area as to overlapwith the light blocking component 71 so that emitted light from thelogic circuit side may be prevented from leaking to the side of thephotodiode PD.

The reason why the light blocking component 71 is formed into a patternhaving the apertures 73 is as follows. If the area of the Cu pattern inthe light blocking component 71 is set large, a recess is generated dueto dishing in the chemical mechanical polishing (CMP). Thus, a gap isgenerated in the bonding between the substrates and sufficient adhesionis not obtained. Alternatively, if pressure for tight adhesion is sethigh so that the gap generation may be prevented, misalignment betweenthe substrates due to strain becomes large and alignment between thepatterns becomes difficult. Therefore, the apertures 73 are provided tolimit the area of the light blocking component 71 so that the recessgeneration may be prevented.

The light blocking component 71 is in direct contact with the surface onwhich no Cu film exits in the bonding surface on the secondsemiconductor chip section side. Thus, the Cu diffusion barrierinsulating film 75 is suitable as the interlayer insulating film facingthe bonding surface in the first semiconductor chip section.

Meanwhile, as shown in FIG. 11, a semiconductor well region 50 is formedin the area to serve as each chip section in the second semiconductorwafer (hereinafter, referred to as the semiconductor substrate) 54formed of e.g. silicon. The plural MOS transistors Tr11 to Tr14configuring the logic circuit 55 are formed in this semiconductor wellregion 50. Here, the MOS transistors Tr11 to Tr14 are represented asrepresentatives as described above. The element isolation region 63 (seeFIG. 5) can be formed at first although not shown in the diagram.

Over the front surface side of the semiconductor substrate 54, theinterconnects 57 [57 a, 57 b and 57 c] formed of the metals M11 to M13of plural layers, i.e. three layers in the present example, are formed,including the electrically-conductive vias 64, by the intermediary ofthe interlayer insulating film 56. The interconnects 57 can be formed bythe dual damascene method. Specifically, a connecting hole and aninterconnect trench by a via-first process are simultaneously formed inthe interlayer insulating film 56, and a Cu diffusion barrier metal filmfor preventing Cu diffusion and a Cu seed film are formed. Thereafter, aCu material layer is buried by a plating method. Examples of the Cudiffusion barrier metal film include Ta, TaN, Ti, TiN, W, WN, Ru, TiZrNfilms, and alloy films containing these materials. Subsequently, theexcess Cu material layer is removed by a chemical mechanical polishing(CMP) method, so that a Cu interconnect monolithic with the planarizedelectrically-conductive via is formed. Thereafter, the Cu diffusionbarrier insulating film is deposited although not shown in the diagram.As the Cu diffusion barrier insulating film, e.g. an insulating film ofSiN, SiC, SiCN, or SiON or benzocyclobutene (BCB: adhesive) as a resincan be used. By repeating this step, the interconnects 57 a to 57 cformed of the metals M11 to M13 of three layers are formed.

Next, as shown in FIG. 12, a first insulating film 82 that does not havethe Cu diffusion barrier character, a second insulating film 83 thatdoes not have the Cu diffusion barrier character, and a Cu diffusionbarrier insulating film 81 are sequentially formed. The first insulatingfilm 82 and the second insulating film 83 are formed of an SiO₂ film, anSiCOH film, etc. As the Cu diffusion barrier insulating film 81, e.g. aninsulating film of SiN, SiC, SiCN, or SiON or benzocyclobutene (BCB:adhesive) as a resin can be used as with the above description. The Cudiffusion barrier insulating film 81, the first insulating film 82, andthe second insulating film 83 are equivalent to the interlayerinsulating film 56. Subsequently, the outermost Cu diffusion barrierinsulating film 81, the second insulating film 83, and the firstinsulating film 82 are patterned to selectively open via holes 86 by avia-first process by using lithography and etching technique.Thereafter, the second insulating film 83 is patterned to selectivelyform apertures 84 and 85. The apertures 84 are formed at such positionsas to cover the apertures 73 of the light blocking component 71 of thefirst semiconductor chip side. It is preferable that this aperture 84 beformed to have such a size as to cover the aperture 73 of the lightblocking component 71 and partially overlap with the light blockingcomponent 71 so that light leakage due to bonding misalignment may beprevented when the first semiconductor substrate is bonded to the secondsemiconductor substrate later.

That is, the films are so patterned as to have the apertures 84 at theparts corresponding to the light blocking component 72 that should beformed, the aperture 85 at the part corresponding to the connectinginterconnect 58 that should be formed, and the via holes 86.

Next, as shown in FIG. 13, the light blocking component 72 having a dotshape, the electrically-conductive vias 64 connected to the interconnect57 c, and the connecting interconnect 58 are formed by burying a Cumaterial in the apertures 84 and 85 and the via holes 86 by use of thedual damascene method as with the above description. The light blockingcomponent 72 and the connecting interconnect 58 are formed by thefourth-layer metal M14. Thereby, the multilayer wiring layer 59 isformed by the interconnects 57 a to 57 c, the connecting interconnect58, the light blocking component 72, which are formed of the metals M11to M14, the interlayer insulating films 56, the Cu diffusion barrierinsulating film 81, the first insulating film 82, and the secondinsulating film 83.

Next, as shown in FIG. 14, the first semiconductor substrate 33 isbonded to the second semiconductor substrate 54 in such a manner thattheir respective multilayer wiring layers are opposed to each other andboth connecting interconnects 36 and 58 are brought into direct contactwith and electrically connected to each other. That is, the first andsecond semiconductor substrates 33 and 54 are physically bonded andelectrically connected to each other. At this time, the light blockingcomponent 71 and the light blocking component 72 are also bondeddirectly to each other at the overlapping part. Specifically, thermaldiffusion bonding between the connecting interconnects 36 and 58 andbetween the light blocking components 71 and 72 is performed by heattreatment. The heat treatment temperature at this time can be set toabout 100° C. to 500° C. Furthermore, the insulating films as theinterlayer insulating films are subjected to surface treatment andbonded to each other by plasma bonding or an adhesive. The Cu surface ofthe connecting interconnects 36 and 58 and the light blocking components71 and 72 is easily oxidized. It is also possible to perform reductiontreatment for removing the oxide film on the Cu surface before thebonding. The reduction treatment can be performed by e.g. a hydrogengas, a mixed gas of hydrogen and argon, hydrogen plasma, ammonia plasma,argon plasma, or the like.

Next, as shown in FIG. 15, the first semiconductor substrate 33 isground and polished from the back surface side to be processed into athin film form by using the CMP method or the like, with the desiredfilm thickness of the photodiode PD left.

Next, as shown in FIG. 16, the light blocking film 39 covering the areaover the photodiodes PD corresponding to the optical black area 41 isformed over the surface of the substrate processed into a thin film formby the intermediary of the insulating film 38. Furthermore, the colorfilter 44 and the on-chip lens 45 are formed over the photodiodes PDcorresponding to the effective pixel area 42 by the intermediary of theplanarizing film 43.

Subsequently, chipping of separating the bonded first and secondsemiconductor substrates 33 and 54 into the respective chips isperformed, so that the intended solid-state imaging device 31 shown inFIG. 3 is obtained.

As the metals M5 and M14 serving as the light blocking components 71 and72, the connecting interconnects 36 and 58, and interconnects of thesame layers as those of them, a material that has high electricalconductivity and high light blocking capability and is easy to bond ispreferable. As a material having such characters, besides Cu, a singlematerial such as Al, W, Ti, Ta, Mo, or Ru or an alloy can be used.

It is preferable to determine the film thickness of the light blockinglayer 68, i.e. the film thickness of the light blocking components 71and 72 in the present example, depending on the wavelength of light onthe side of the second semiconductor chip section 26 involving lightemission. In the present embodiment, light emitted from hot carriers ofthe MOS transistor of the second semiconductor chip section 26 should beblocked. Therefore, the light blocking layer thickness should bedesigned in consideration of light having a wavelength of about 1 μm.For example, the film thickness of the light blocking layer 68 and hencethe film thickness of the light blocking components 71 and 72 can be setto about 50 nm to 800 nm.

FIG. 17 shows the dependence of the transmittance on the lightwavelength regarding Cu, Ta, Ti, Ru, W, and AlSi at specific filmthicknesses. A curve a1 corresponds to a Cu film having a film thicknessof 50 nm. A curve b1 corresponds to a Ta film having a film thickness of50 nm. A curve c1 corresponds to a Ti film having a film thickness of 50nm. A curve d1 corresponds to a Ru film having a film thickness of 62nm. A curve e1 corresponds to a W film having a film thickness of 60 nm.A curve f1 corresponds to an AlSi film having a film thickness of 60 nm.Based on the graph of FIG. 17, a metal film that is suitable to blocklight having a wavelength of 300 nm to 1 μm can be selected.

FIG. 18 shows the dependence of the transmittance on the film thicknessregarding Cu, Ta, Ti, Ru, and W at specific wavelengths of light. Astraight line a2 shows the character of a Cu film at a wavelength of 575nm. A straight line b2 shows the character of a Ta film at a wavelengthof 700 nm. A straight line c2 shows the character of a Ti film at awavelength of 700 nm. A point d2 shows the character of a Ru film at awavelength of 700 nm. A straight line e2 shows the character of a W filmat a wavelength of 700 nm. Based on the graph of FIG. 18, the filmthicknesses of the respective metal films to obtain the desired lightblocking rate can be selected. Also in the case of blocking emittedlight near a wavelength of 1 μm due to hot carriers from a transistor,the film thickness can be selected by a similar method.

In the solid-state imaging device 31 and the manufacturing methodthereof according to the first embodiment, the light blocking layer 68formed of the metals M5 and M14 of the same layers as those of theconnecting interconnects 36 and 58 is formed near the bonding betweenthe first semiconductor chip section 22 and the second semiconductorchip section 26. This light blocking layer 68 can suppress the incidenceof emitted light due to hot carriers from the MOS transistor of thelogic circuit 55 of the second semiconductor chip section 26 on thepixel array of the first semiconductor chip section 22. Therefore, theadverse effects of the light emission due to the hot carriers aresuppressed and thus dark current and random noise can be suppressed.

Because the light blocking layer 68 is formed by the metals M5 and M14of the same layers as those of the connecting interconnects 36 and 58,the thickness of the whole bonded semiconductor chip can be set smallerthan that of the related-art example of FIG. 22 and the thickness of thesolid-state imaging device 31 can be further reduced. This can provide asolid-state imaging device having less dark current and random noisewithout increasing the thickness of the whole semiconductor chip.

In the first semiconductor chip section 22, the interconnect 35 d 1formed of the metal M4 connected to the connecting interconnect 36 viathe electrically-conductive vias 52 is so formed as to be extended tothe side of the light blocking component 71 and overlap with the lightblocking component 71. This can prevent emitted light from the secondsemiconductor chip section 26 from leaking to the pixel array through agap.

In the manufacturing method, the interconnects, the connectinginterconnects, and the light blocking layer can be simultaneouslyformed. Thus, reduction in the number of manufacturing steps, reductionin the mask step, and reduction in the material cost are achieved and asolid-state imaging device having less dark current and random noise canbe manufactured at low cost. In the forming of the via holes 80 in thestep of FIG. 9, the via holes 80 can be easily formed because the aspectratio of the via hole is lower than that in the related-art example ofFIG. 22.

In the bonding between the first semiconductor substrate 33 and thesecond semiconductor substrate 54, so-called intermetallic bonding suchas bonding between the connecting interconnects and bonding between thelight blocking components is obtained with a high area ratio. Therefore,high bonding strength is obtained and abnormalities due to filmseparation are suppressed. Thus, a solid-state imaging device can bemanufactured at a high yield.

Metal layers having a large area, i.e. the connecting interconnects 36and 58 and the light blocking layer 68, exist between the first andsecond semiconductor chip sections 22 and 26. Thus, heat radiation fromthe logic circuit 55 can be dispersed and the rise of the temperature onthe pixel array side can be suppressed. Therefore, it is possible toprovide a solid-state imaging device free from characteristicdeterioration such as dark current of the pixel array when the operatingtemperature rises.

The light blocking layer 68 is formed of the light blocking component 71having the apertures 73 for one side and the light blocking component 72having a shape of dots covering the apertures 73 for the other. Due tothis feature, the areas of both light blocking components 71 and 72 canbe set small. Thus, a recess due to chemical mechanical polishing (CMP)in the forming of the light blocking components is not generated, whichprovides favorable bonding between both semiconductor chip sections 22and 26.

Modification Example of Light Blocking Layer

Various shapes are possible as the shapes of the light blockingcomponent on the side of the first semiconductor chip section 22 and thelight blocking component on the side of the second semiconductor chipsection 26. FIGS. 19A to 19C show a modification example of the lightblocking layer. A light blocking component 88 on the side of the firstsemiconductor chip section 22 is formed into a shape of plural stripsthat have a requisite width W1 and are arranged at a requisite intervalt1 (see FIG. 19A). A light blocking component 89 on the side of thesecond semiconductor chip section 26 is formed into a shape of pluralstrips that have a requisite width W2 (>W1) larger than theabove-described width W1 and are arranged at a requisite interval t2(<t1) smaller than the above-described interval t1 (see FIG. 19B). Thepitch of the strip part of the light blocking component 88 is set equalto that of the strip part of the light blocking component 89. The lightblocking layer 68 is formed by overlapping the strip-manner lightblocking component 88 and the strip-manner light blocking component 89with each other in such a manner that the surface is uniformly coveredin top view (see FIG. 19C). The solid-state imaging device having such alight blocking layer 68 also has the same advantageous effects as thosedescribed above.

3. Second Embodiment Configuration Example of Solid-State Imaging Device

FIG. 20 shows a solid-state imaging device according to anotherembodiment of the present disclosure, specifically a back-illuminatedCMOS solid-state imaging device according to a second embodiment of thepresent disclosure. In a solid-state imaging device 91 according to thesecond embodiment, a light blocking layer 92 is formed on the side ofthe first semiconductor chip section 22 by the metal M5 of the samelayer as that of the connecting interconnect 36. This light blockinglayer 92 is formed uniformly over the whole surface. Even when a recessis generated due to dishing in chemical mechanical polishing (CMP) inthe forming of the light blocking layer 92, which is uniform across thewhole surface, bonding is enabled by increasing the pressure for tightadhesion.

The other configuration is the same as that of the first embodiment.Therefore, the same part as that in FIG. 3 is given the same symbol andoverlapping description is omitted.

The light blocking layer 92, which is uniform across the whole surface,can be provided in either one or both of the first semiconductor chipsection 22 and the second semiconductor chip section 26.

Manufacturing Method Example of Solid-State Imaging Device

The solid-state imaging device 91 according to the second embodiment canbe manufactured based on the manufacturing method of the firstembodiment except for that the pattern shape of the light blocking layerof the first embodiment is changed.

The solid-state imaging device 91 and the manufacturing method thereofaccording to the second embodiment have the same advantageous effects asthose described for the first embodiment. Specifically, the lightblocking layer 92 formed of the metal M5 or/and M14 of the same layer asthat of the connecting interconnect 36 or/and 58 is formed near thebonding between the first semiconductor chip section 22 and the secondsemiconductor chip section 26. This light blocking layer 92 can suppressthe incidence of emitted light due to hot carriers from the MOStransistor of the logic circuit 55 of the second semiconductor chipsection 26 on the pixel array of the first semiconductor chip section22. Therefore, the adverse effects of the light emission due to the hotcarriers are suppressed and thus dark current and random noise can besuppressed.

Because the light blocking layer 92 is formed by the metal M5 or/and M14of the same layer as that of the connecting interconnect 36 or/and 58,the thickness of the whole bonded semiconductor chip can be set smallerthan that of the related-art example of FIG. 22 and the thickness of thesolid-state imaging device 91 can be further reduced. This can provide asolid-state imaging device having less dark current and random noisewithout increasing the thickness of the whole semiconductor chip.

In the first semiconductor chip section 22, the interconnect 35 d 1formed of the metal M4 connected to the connecting interconnect 36 viathe electrically-conductive via 52 is so formed as to be extended to theside of the light blocking layer 92 and overlap with the light blockinglayer 92. This can prevent emitted light from the second semiconductorchip section 26 from leaking to the pixel array through a gap.

In the manufacturing method, the interconnects, the connectinginterconnects, and the light blocking layer can be simultaneouslyformed. Thus, reduction in the number of manufacturing steps, reductionin the mask step, and reduction in the material cost are achieved and asolid-state imaging device having less dark current and random noise canbe manufactured at low cost. When the light blocking layer 92 isprovided in the first semiconductor chip section 22 side, the via holes80 can be easily formed because the aspect ratio of the via hole islower than that in the related-art example of FIG. 22.

In the bonding between the first semiconductor substrate 33 and thesecond semiconductor substrate 54, so-called intermetallic bonding suchas bonding between the connecting interconnects and bonding between thelight blocking layers is obtained with a high area ratio. Therefore,high bonding strength is obtained and abnormalities due to filmseparation are suppressed. Thus, a solid-state imaging device can bemanufactured at a high yield.

Metal layers having a large area, i.e. the connecting interconnects 36and 58 and the light blocking layer 92, exist between the first andsecond semiconductor chip sections 22 and 26. Thus, heat radiation fromthe logic circuit 55 can be dispersed and the rise of the temperature onthe pixel array side can be suppressed. Therefore, it is possible toprovide a solid-state imaging device free from characteristicdeterioration such as dark current of the pixel array when the operatingtemperature rises.

The above-described respective embodiments can also employ theconfiguration of FIG. 2C.

The above-described respective embodiments have the configuration inwhich two semiconductor chip sections 22 and 26 are bonded to eachother. The solid-state imaging device according to one embodiment of thepresent disclosure can also have a configuration in which three or moresemiconductor chip sections are bonded to each other. For example, it isalso possible to configure the solid-state imaging device by threesemiconductor chip sections, i.e. a third semiconductor chip sectionhaving a memory circuit in addition to the first semiconductor chipsection having the pixel array and the second semiconductor chip sectionhaving the logic circuit. In this case, at least the configuration ofthe first and second semiconductor chip sections is a configurationincluding the above-described light blocking layer 68 or 92.

4. Third Embodiment Configuration Example of Electronic Apparatus

The solid-state imaging devices according to the above-describedembodiments of the present disclosure can be applied to electronicapparatus such as camera systems typified by digital cameras and videocamcorders, cellular phones having an imaging function, and other piecesof apparatus having an imaging function.

FIG. 21 shows a camera as one application example of electronicapparatus according to a third embodiment of the present disclosure. Thecamera according to the present embodiment is a video camcorder capableof photographing a still image or a moving image as an example. A camera101 of the present embodiment has a solid-state imaging device 102, anoptical system 103 that guides incident light to a light receivingsensor section of the solid-state imaging device 102, and a shutterdevice 104. Furthermore, the camera 101 has a drive circuit 105 thatdrives the solid-state imaging device 102 and a signal processingcircuit 106 that processes an output signal of the solid-state imagingdevice 102.

As the solid-state imaging device 102, any of the solid-state imagingdevices of the above-described respective embodiments is employed. Theoptical system (optical lens) 103 forms an image on the imaging plane ofthe solid-state imaging device 102 based on image light (incident light)from a subject. Thereby, a signal charge is accumulated in thesolid-state imaging device 102 for a certain period. The optical system103 may be an optical lens system composed of plural optical lenses. Theshutter device 104 controls the period of light irradiation to thesolid-state imaging device 102 and the period of light blocking. Thedrive circuit 105 supplies a drive signal to control the transferoperation of the solid-state imaging device 102 and the shutteroperation of the shutter device 104. Signal transfer of the solid-stateimaging device 102 is performed based on the drive signal (timingsignal) supplied from the drive circuit 105. The signal processingcircuit 106 executes various kinds of signal processing. A video signalresulting from the signal processing is stored in a storage medium suchas a memory or output to a monitor.

The electronic apparatus according to the third embodiment includes theback-illuminated solid-state imaging device according to any of theabove-described embodiments of the present disclosure. Thus, lightemitted by hot carriers from the MOS transistor of the logic circuit isnot incident on the pixel array side and dark current and random noisecan be suppressed. Therefore, electronic apparatus with high imagequality can be provided. For example, a camera with improved imagequality and so forth can be provided.

Configuration Example of Semiconductor Device

The above-described light blocking layers 68 and 92 can be also appliedto a semiconductor device obtained by bonding two semiconductor chipsections having a semiconductor integrated circuit to each other. Forexample, a first semiconductor chip section having a first logic circuitand a second semiconductor chip section having a second logic circuitare bonded to each other to configure a semiconductor device, althoughnot shown in a diagram. Each of the first logic circuit and the secondlogic circuit is formed by plural MOS transistors. The first and secondsemiconductor chip sections each have a multilayer wiring layer and areso bonded that both multilayer wiring layers are opposed to each other.In this configuration, a light blocking layer is formed by metals of thesame layers as those of interconnects of the multilayer wiring layers asdescribed in the first and second embodiments, and the metals arebrought into direct contact with and mechanically and electricallyconnected to each other.

According to this semiconductor device, light emitted by hot carriersfrom the MOS transistor of one logic circuit is blocked by the lightblocking layer and the adverse effects on the other logic circuit can besuppressed.

A configuration having a light blocking layer similar to that of theabove-described semiconductor device can be applied also to asemiconductor device obtained by bonding a first semiconductor chipsection having a logic circuit and a second semiconductor chip sectionhaving a memory circuit to each other. Also in this semiconductordevice, light emitted by hot carriers from the MOS transistor of thelogic circuit is blocked by the light blocking layer and the adverseeffects on the memory circuit can be suppressed.

The present disclosure contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2011-024954 filed in theJapan Patent Office on Feb. 8, 2011, the entire content of which ishereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A solid-state imaging device comprising: a firstsemiconductor substrate including a pixel array and a first multilayerwiring layer having a first connecting interconnect; a secondsemiconductor substrate including a logic circuit and a secondmultilayer wiring layer having a second connecting interconnect, whereinthe first semiconductor substrate and the second semiconductor substrateare arranged such that the first multilayer wiring layer and the secondmultilayer wiring layer face one another and are electrically connectedto one another at a bonding surface between the first semiconductorsubstrate and the second semiconductor substrate; and a light blockinglayer including a first electrically-conductive film of the same layeras one of the first connecting interconnect and the second connectinginterconnect, formed across a whole of the bonding surface correspondingto the logic circuit, wherein the solid-state imaging device is aback-illuminated solid-state imaging device.
 2. The solid-state imagingdevice according to claim 1, wherein the light blocking layer furthercomprises a second electrically-conductive film of the same layer as theother of the first connecting interconnect and the second connectinginterconnect.
 3. The solid-state imaging device according to claim 1,wherein the first multilayer wiring layer further comprises a firstmetal wiring, wherein the first metal wiring overlaps with the lightblocking layer.
 4. The solid-state imaging device according to claim 3,wherein the first multilayer wiring layer further comprises anelectrically-conductive via between the first connecting interconnectand the first metal wiring.
 5. The solid-state imaging device accordingto claim 1, wherein the first connecting interconnect and the secondconnecting interconnect are directly bonded to one another at a bondingportion.
 6. The solid-state imaging device according to claim 1, whereina material of the light blocking layer is selected from the groupincluding Cu, Al, W, Ti, Ta, Mo, Ru, and alloys thereof.
 7. Thesolid-state imaging device according to claim 1, wherein a filmthickness of the light blocking layer is between 50 and 800 nm.
 8. Amethod of manufacturing a solid-state imaging device, the methodcomprising: providing a first semiconductor substrate including a pixelarray and a first multilayer wiring layer having a first connectinginterconnect; providing a second semiconductor substrate including alogic circuit and a second multilayer wiring layer having a secondconnecting interconnect; arranging the first semiconductor substrate andthe second semiconductor substrate such that the first wiring layer andthe second multilayer wiring layer a face one another and areelectrically connected to one another at a bonding surface between thefirst semiconductor substrate and the second semiconductor substrate;and providing a light blocking layer including a firstelectrically-conductive film of the same layer as one of the firstconnecting interconnect and the second connecting interconnect uniformlyacross a whole of the bonding surface corresponding to the logiccircuit, wherein the solid-state imaging device is a back-illuminatedsolid-state imaging device.
 9. The method of manufacturing a solid-stateimaging device according to claim 8, wherein the light blocking layerfurther comprises a second electrically-conductive film of the samelayer as the other of the first connecting interconnect and the secondconnecting interconnect.
 10. The method of manufacturing a solid-stateimaging device according to claim 8, wherein the first multilayer wiringlayer further comprises a first metal wiring, wherein the first metalwiring overlaps with the light blocking layer.
 11. The method ofmanufacturing a solid-state imaging device according to claim 10,wherein the first multilayer wiring layer further comprises anelectrically-conductive via between the first connecting interconnectand the first metal wiring.
 12. The method of manufacturing asolid-state imaging device according to claim 8, further comprising:directly bonding the first connecting interconnect and the secondconnecting interconnect to one another at a bonding portion.
 13. Themethod of manufacturing a solid-state imaging device according to claim8, wherein a material of the light blocking layer is selected from thegroup including Cu, Al, W, Ti, Ta, Mo, Ru, and alloys thereof.
 14. Anelectronic apparatus comprising: a solid-state imaging device; anoptical system configured to guide incident light to a photoelectricconverter of the solid-state imaging device; and a signal processingcircuit configured to process an output signal of the solid-stateimaging device, wherein the solid state imaging device includes: a firstsemiconductor substrate including a pixel array and a first multilayerwiring layer having a first connecting interconnect, a secondsemiconductor substrate including a logic circuit and a secondmultilayer wiring layer having a second connecting interconnect, whereinthe first semiconductor substrate and the second semiconductor substrateare arranged such that the first multilayer wiring layer and the secondmultilayer wiring layer face one another and are electrically connectedto one another at a bonding surface between the first semiconductorsubstrate and the second semiconductor substrate, and a light blockinglayer including a first electrically-conductive film of the same layeras one of the first connecting interconnect and the second connectinginterconnect, formed across a whole of the bonding surface correspondingto the logic circuit, wherein the solid-state imaging device is aback-illuminated solid-state imaging device.
 15. The electronicapparatus according to claim 14, wherein the light blocking layerfurther comprises a second electrically-conductive film of the samelayer as the other of the first connecting interconnect and the secondconnecting interconnect.
 16. The electronic apparatus according to claim14, wherein the first multilayer wiring layer further comprises a firstmetal wiring, wherein the first metal wiring overlaps with the lightblocking layer.
 17. The electronic apparatus according to claim 16,wherein the first multilayer wiring layer further comprises anelectrically-conductive via between the first connecting interconnectand the first metal wiring.
 18. The electronic apparatus according toclaim 14, wherein the first connecting interconnect and the secondconnecting interconnect are directly bonded to one another at a bondingportion.
 19. The electronic apparatus according to claim 14, wherein amaterial of the light blocking layer is selected from the groupincluding Cu, Al, W, Ti, Ta, Mo, Ru, and alloys thereof.
 20. Theelectronic apparatus according to claim 14, wherein a film thickness ofthe light blocking layer is between 50 and 800 nm.